Traditional window units utilize a screen permanently attached to a screen frame. The result is that the screen is always obstructing the view through the window even when the window is closed and the screen is not needed. In the traditional window screen, the screen and screen frame must be removed from the window and placed in storage to eliminate this obstruction to the view. U.S. Pat. No. 5,915,443 discloses a window screen that can be concealed in the bottom lateral member of the sash of a hung window and unwound as the sash is raised thus providing an automatic window screen.